Custom Ubuntu command using bash scripts

• Open a terminal window using

  Ctrl+Alt+T

• Run the command

  gedit ~/.profile

• Add the line
  

  export PATH=$PATH:/example/path/bin

  to the bottom and save
  
• Log out and log in again. If you want to use it immediately in the terminal already opened
  

  source ~/.profile

Edit:
A safer way is to use quotes. Doing so is necessary if one or more directories in the original PATH contain spaces. So:

export PATH="$PATH:/example/path/bin"